Drillable Bit Nozzle Retainer with Interchangeable Nozzle Capability

ABSTRACT

A drillable bit nozzle assembly can be used on a casing drilling bit and features a support housing preferably of the same material as the bit crown. The housing is preferably attached by welding and contains a groove for a seal and internal threads for an insert retainer. A landing shoulder for the hardened inserts allows different sizes to be inserted in the housing and retained by a hardened or carbide ring holder that engages the internal threads. The insert and the retainer are sufficiently thin walled to break during mill out while the housing is softer and easily milled out.

FIELD OF THE INVENTION

The field of the invention is drillable nozzles in bits and more particularly a holder that is softer than the nozzle insert and further has the capability of accepting different nozzle sizes in the field.

BACKGROUND OF THE INVENTION

In some applications the bit is not recovered to the surface and must be drilled out to further extend a well. One example of such an application is a bit secured to the lower end of a casing string and the string is advanced as more hole is made. To extend the well further after the casing is delivered, the bit at the bottom of the casing needs to be removed, usually by drilling out. Drill bits typically contain hardened nozzles that circulate fluid to remove the cuttings and bring them to the surface with the circulating mud or other drilling fluid. The circulating fluid also keeps the bit components cool to counteract the heat created from the drilling process.

Drillable inserts have been used before as illustrated in U.S. Pat. No. 6,848,517 where the assembly of a soft body 3 with a layer of hardened material 5 inside is threaded to the bit at thread 2. The nozzle size 4 a, 4 b is predetermined for a given body 3. There are similar designs that use a different nozzle size for a given body of a softer exterior and a passage lined with a hardened material but instead secure the assembly to the bit with a snap ring. Examples of this design with the snap ring identified in brackets are U.S. Pat. No. 3,111,179 (16); 4,392,534 (6) and 2,855,182 (11), note this reference has no hardened liner.

What is lacking and provided by the present invention is a holder preferably compatible with the bit crown material that can accommodate a variety of nozzle sizes to avoid having to keep an inventory of different nozzle sizes in similar sized bodies. An easier way of attaching the holder is also provided. Those skilled in the art will better understand the invention from a review of the description of the preferred embodiment and the associated FIGURE while understanding that the claims, including their literal and equivalent scope, are the full measure of the invention.

SUMMARY OF THE INVENTION

A drillable bit nozzle assembly can be used on a casing drilling bit and features a support housing preferably of the same material as the bit crown. The housing is preferably attached by welding and contains a groove for a seal and internal threads for an insert retainer. A landing shoulder for the hardened inserts allows different sizes to be inserted in the housing and retained by a hardened or carbide ring holder that engages the internal threads. The insert and the retainer are sufficiently thin walled to break during mill out while the housing is softer and easily milled out.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a part section through the bit body showing the housing secured to the body with an insert held in position by a threaded retainer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A portion of the bit 10 is illustrated with a passage 12 into which a housing 14 preferably made from the same material of the crown (not shown) of the bit 10 such as 1018 steel, for example. A weld 16 joins the housing 14 to the bit 10 after a shoulder 18 on the housing 14 lands on a mating shoulder 20 formed in passage 12. The housing 14 has an outlet 22 and a seal groove 24 above. An o-ring or some other type of seal 26 is inserted into groove 24 after weld 16 is made to secure the position of the housing 14 and the weld 16 is cleaned up, as needed. After seal 26 is in groove 24 a nozzle 28 having a tapered passage 30 of predetermined dimensions can be dropped in and secured with retainer 32 at thread 34. The nozzle 28 and the retainer 32 are harder than the material for the housing 14 and carbide is the preferred material for both. Carbide for these two items will still mill out easily because the wall thickness of these parts is fairly small causing these parts to fragment and fall apart during milling. Passage 36 in the retainer 32 and the continuation into passage 30 provides a hardened surface against the bulk of the flowing mud or other drilling fluid that passes through while at the same time keeping the bulk of the internal wall of the housing 14 protected from erosive fluid flow.

Those skilled in the art will appreciate that while the preferred mode of securing the retainer 32 is threads 34 that other ways of fixating the retainer 32 are contemplated. A spring loaded bayonet connection can be used to hold the retainer to the housing 14. A J-slot mechanism is another way. The two can be made in an interference fit and simply pressed together or some flexible retainer engaging a groove such as a snap ring can be used. As another option the retainer 32 can be eliminated and the nozzle 28 can be pressed into contact with inner wall such as 42 in an interference fit.

Nozzle bodies 28 having similar outside dimensions so as to land on shoulder 38 with a flange 40 can be selected with different dimensions for the passage 30 so that the same housing 14 can accommodate drop in inserts 28 that have different flow or pattern characteristics and this can be done in a field location. This is to be compared to the prior designs that used a soft body for each nozzle passage size so that changing nozzles in the field required the entire assembly of the soft outer housing and the lined passage of hardened material unique to a given body to all be replaced for every nozzle opening in the bit. As illustrated in the FIGURE with the present invention a housing 14 is secured with a weld 16 to the bit 10 and thereafter an array of different nozzles can be lowered through opening 22 and have a flange 40 that lands on shoulder 38. The same retainer 32 works for every different nozzle 28 that is inserted in housing 14.

While housing 14 is preferably welded into position at 16 other ways to secure it are contemplated such as an interference fit and pressing in the housing 14 until it shoulders on bit shoulder 20 as one example. Groove 24 can be eliminated and a seal can be placed on top of shoulder 38 to reduce production cost for a separate groove 24. Optionally, a separate seal between the insert 28 and the housing 14 can be eliminated altogether.

While the preferred embodiment has been set forth above, those skilled in art will appreciate that the scope of the invention is significantly broader and as outlined in the claims which appear below. 

1. A downhole drill bit with a drillable nozzle assembly, comprising: a body having at least one passage; at least one nozzle housing in said passage, said housing accepting one of a plurality of nozzle bodies that have differing flow paths therethrough.
 2. The bit of claim 1, wherein: said nozzle housing is made of a softer material than said nozzle body.
 3. The bit of claim 1, wherein: said nozzle housing is welded to said passage
 4. The bit of claim 1, wherein: said passage comprises a landing shoulder and said nozzle housing has a radial surface that lands on said shoulder to locate said nozzle housing in said passage.
 5. The bit of claim 1, wherein: said nozzle housing further comprises an internal landing shoulder; said nozzle bodies are all adapted to land on said shoulder.
 6. The bit of claim 5, further comprising: a retainer removably mounted within said nozzle housing to secure a nozzle body to said shoulder.
 7. The bit of claim 6, wherein: said retainer is made of the same material as said nozzle body.
 8. The bit of claim 6, wherein: said retainer is held by threads.
 9. The bit of claim 6, further comprising: an outlet opening in said nozzle housing, all of said nozzle bodies configured to extend through said outlet opening when landed on said shoulder; a seal between said mounted nozzle body and said nozzle housing.
 10. The bit of claim 6, wherein: said nozzle bodies comprise an exterior flange located on an end thereof having an outer dimension that allows landing on said shoulder.
 11. The bit of claim 10, wherein: said retainer and said nozzle bodies are made of carbide.
 12. The bit of claim 1, wherein: said nozzle body is held to said nozzle housing by an interference fit.
 13. The bit of claim 1, wherein: said nozzle housing is held to said body by an interference fit.
 14. The bit of claim 6, wherein: said retainer is held to said nozzle housing by an interference fit.
 15. The bit of claim 6, wherein: said retainer comprises a ring shape with a through passage aligned with the flow path of a nozzle body that it secures.
 16. The bit of claim 15, wherein: said ring has an exterior thread for engagement to said nozzle housing.
 17. The bit of claim 15, wherein: said ring is retained to said nozzle housing with a snap ring.
 18. The bit of claim 15, wherein: said ring is retained to said nozzle housing with a pin and slot assembly. 